My 92 Accord left signal indicator light on the dash started blinking really fast indicating (as I was trying to signal left) that the bulb wasn't lighting. I stopped and got out and turned on the left signal and visually checked and saw that indeed it wasn't working. I looked at the bulb it looked fine but I changed it out anyway with a new one but that didn't fix the issue. The socket and contacts within look fine, not corroded or anything. I tried turning on the emergency flashers and saw that still that same bulb on that left side) which is the same one as the left turn signal bulb) was not lighting.
I haven't bothered to look at the turn signal fuse, figuring if that was bad that both sides wouldn't be lighting. I considered the possibility of a bad turn signal relay but likewise I would think if that was bad neither side would be working.
When I turn on the headlights, both rear taillights light fine, and when I brake both sides light fine too.

What might be the next logical step here to in troubleshoot/fix this?

 

Grab a volt meter and remove the non-working bulb.

Connect the black volt meter lead to a good ground (any bare metal bolt will work).

One wire should get 12V pulses when you touch the red meter lead to it, when you have the turn signal turned on.

The other wire (I'm guessing black) will have ~0 ohms resistance when you switch the meter to ohms. Keep the black meter lead connected to ground and touch the red meter lead to the ground (black?) wire.

Also try doing this testing on a working turn signal bulb, so you are sure you are using you meter properly.

 

OK thanks PA. I grabbed a volt meter, and tested doing just as you advised. I got the 12V pulses with the one wire and the 0 ohms resistance with the other wire, doing as you described. However, while doing this testing and upon closer examination I discovered I was mistaken before about no apparent corrosion of the socket/connection. Indeed there was rusty corrosion down in there where the black wire is connected close there to the bulb socket cylinder or whatever it might be called. I did my best with a tiny little screwdriver to scrape/dig that rusty stuff off out/off. That seemed to do the trick, got the signal bulb working. Then upon replacing the socket harness back into the lens fixture I tried it again, but it wouldn't work, again. So I pulled it out again, scraped that spot down in there again, and apparently managed to scrape enough away to get the bulb/signal working again, all the time now. Still though, I can see that I can't get rid of all that rust down in that cranny, so to avoid future problem with it again soon will probably need to replace that socket/wire assembly with a new one I suppose.

 

Glad you figured it out and it was a relatively simple fix.

If the problem returns, get creative with some sandpaper to clean off the corrosion.

 

Yeah I'm glad a simple cause/fix too. Not sure though that I could really get creative enough with some sandpaper to get it down into that tiny cranny there next to the wire end and the plastic socket housing. And I can see down in there that some of that rust/corrosion whatever you wanna call it seems to be within the strands of the end of the black wire itself where its connected right there tight by the socket. It's not particularly heavy rust/corrosion; I was thinking it might not hurt (or maybe even help) to squirt a little blast of WD40 down in there. That might kinda break down the rusty-ness. That two-socket factory assembly part with the connector isn't made where you can take it apart and try to clean it up and put it back together and reconnect the wire, without ruining it. I noticed a new one cost 20 bucks minimum, comparing costs online. Part
33552-SM4-A01